


Sonic Synergy

by CalorisBerlioz



Category: Sonic the Hedgehog (Video Games)
Genre: Action/Adventure, Alternate Universe, Friendship, Gen, Science Fiction, Slow Build, Suspense
Language: English
Status: In-Progress
Published: 2018-10-20
Updated: 2019-01-11
Packaged: 2019-08-04 17:24:35
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 10
Words: 11,225
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/16350965
Author URL: https://archiveofourown.org/users/CalorisBerlioz/pseuds/CalorisBerlioz
Summary: Everybody needs a vacation - some people even deserve one. Too bad heroes never get to catch a break. With Shadow's mysterious reappearance after the events of Sonic Adventure 2 and a series of storms battering the island of Adabat, there's something fishy going on beneath the waves. And this time, it's a little more than Chaos.





	1. Resort Island

**Author's Note:**

> A big thank you to my bestest friend in the whole universe, who beta read some of this and supported me till the very end. She owes me a dime now.

The water sparkled in the brilliant sunshine, dotted by pools of green where algae coated the rocks. Sonic shielded his eyes, pupils tracing over the waves and into the horizon. He heaved a sigh of relief. He didn’t have to worry about comic book agents or badniks or reporters or anybody, they’d never get him out here.

“Sonic! Hey Sonic!”

A pair of fluffy tails glowed in the white sunlight, glossy with good health. A metal toolbox clunked against thin legs.

“Oh, hey Tails,” he breathed.

“Come take a look at what I’ve added to the Tornado!” Tails said. Sonic shrugged and nodded his head.

“Sure thing. Hey, have you seen my sunglasses?”

“No, I haven’t, but that’s not important right now. You gotta see this!”

He followed the sound of Tail’s clanging footsteps. They stopped in front of the biplane and Tails turned to undulate towards… whatever it was that was so special.

“Well, it looks the same as it did yesterday. Nice!” Sonic snickered. Tails rolled his eyes and slammed the open hatch shut, ears pressed to the top of his head.

“Allow me to introduce you, Sonic, to the new and improved Tornado-1!”

The whole world rumbled and quaked with the plane’s wild dancing, its body compacted into a bullet shape. Sonic’s eyes watered against the blistering heat and the high-pitched squealing. Shards of sand stung their skin. Recoated red and yellow wings folded into a neat X shape, the plane’s wheels disappearing beneath the cockpit. In a flash the plane sat still, and the vibrations rumbling through their bones settled to a purr.

“Woah…”

“It’s the latest in high-flying weaponised technology, complete with charge blasts for maximum damage,” Tails grinned, rocking on the balls of his feet. Sonic ran a hesitant finger over one of the cannon barrels and snapped back. The tip of his glove was charred. Sonic circled the plane and stopped before the propeller, nodding his approval. “I see you’re staying active this summer.”

“It’s the least I can do. I’m still working on the boat upgrade but I can’t finish it until the tides go down, it’s too risky to take it out in the storms,” Tails said. Sonic peered up at the sky.

“The weather has been pretty weird this year. Lots of rain,” he frowned. His blue spikes dunked into the cockpit and muffled the rest of his observations, several pairs of shorts and sandals flying onto the sand behind him. Tails scrambled to catch the falling articles.

“Hey, I found my sunglasses! Great work Tails, the new Tornado’s super cool.”

“Thanks! I hope the waves calm down, it looks like we might have a hurricane,” Tails pointed at the steel clouds pillowing on the horizon. He didn’t remember those being there before… 

He looked around and blinked. 

“Sonic! Don’t forget to wear sunscreen!”

Sonic waved a hand, not bothering to turn back. He picked out a place to doze and flopped down, spines bent comfortably against smooth, sun-soaked rock. Every inhale brimmed with the smell of salt and sand. A pineapple-scented breeze whipped against his face. The surf crashed in frothy white waves against the rock, the spray of sea foam cool on his tanning flesh. He stretched his sore legs and sat up.

A sweaty hand reached to unstrap his shiny red sneakers. His yanking scraped them against the healing blisters and sores on the back of his ankle and stung horribly, making him wince. Once the shoes were tugged from his swollen feet he threw them as hard as he could in an unseen direction. His socks were, fortunately, much more pleasant to remove. He pulled his sunglasses down over his eyes and peered into the celestial blueness of the sea. Hesitant, but determined, he dipped a clownishly over-sized foot into the depths. The water swirled around his feet. As his skin adapted to the temperature he found it to be incredibly soothing, warm as liquid sunshine bouncing against his shins. It was… relaxing.

He lay back against the rock and closed his eyes. The sun beat down on his exposed belly but he couldn’t care to wear any sunscreen. He kept his mind a total blank, the sound of wind in the palms and the roaring of waves now music to his soul, interrupted only occasionally by Tails’s hammering on the Tornado.

One ear flicked. Tails was always so loud. Clingy, too. He was a great kid, and probably smart enough to actually take over the world, but boy would he kill to get some space every once in awhile.

The thoughts echoed in his brain and disintegrated into the water. All the soreness and tension in his muscles melted away with the last of his stress, and as his mind slipped further into the depths he began to reflect on just how great it felt to be off his feet. This vacation was exactly what he needed. The perfect reward for all the good things he’d been doing. And for once he didn’t have to share it with anybody. This trip was all about him…

His ear flicked again, this time with a hint of agitation. He let his body soak into the hot rock and clean ripples of sand. He felt as if he were bobbing in a warm bath, completely motionless. Drifting away. Not a single care in the world. His heavy eyelids sank together into a curtain of dark orange, and the farther he slipped into unconsciousness the deeper his breathing became. He was a rock, sinking slowly to the bottom of the ocean…

“Sonic! Sonic listen here!”

A deep, husky call flipped him from his doze. The blurred shape of a familiar echidna hit him full force and flung him to the hot beach. He scrabbled through the sand, fingers grasping for those stupid shoes.

Knuckles laughed heartily and clapped him on the back, wincing as he pricked his hand on one of the spines.

“Whoa, you’re totally naked!”

Sonic scowled and forced his shoes back on, a blush burning in his muzzle. Knuckles flipped a long red ponytail over his shoulder and crossed his arms, beige cowboy hat pulled over his brows. He shooed his eyes away from Knuckles’ gaze.

“I see you’ve brought back the rodeo clown look. What’s with the ponytail?” Sonic smirked.

Knuckles glared at him from under the brim of his hat.

“I get hot. It’s not a ponytail I just have my spines up.”

“Mhm, sure. What are you doing away from the master emerald?”

“I got some suspicious readings and sensed someone was tampering with the chaos rings. Business as usual, huh?”

“Chaos… rings..?” Sonic asked.

Knuckles clapped Sonic’s shoulder again and shot him a violet stare.

“Well, Sonic, looks like we’re going to be stuck together. What do we have to do around here? Been to any good restaurants?”

“Hey! Don’t change the subject like that!”


	2. Me, Myself... and You

**Summary for the Chapter:**

> Oh snap it's really hitting the fan now, boys.

In less than a minute the three were walking up toward the resort town. They twirled to observe the bustling boardwalk. Each of the buildings’ coy exteriors lay hidden behind vibrant ribbons. Through a wooden arch a bustling crowd greeted them with percussive measures of music, faces plastered with smiles. Adabatan flags waved to their arrival. They bumped through the crowd and paused in front of a small souvenir shop, glancing at the colourful strings of lanterns laced overhead. The ancient ruins were always in view, stretching towards the sky like stony fingers. A massive palm tree in the centre of the town shielded them from the sun. Lines of floating lanterns bobbed in the shallow water surrounding the tree, huge flowers cupping their fragile frames. 

“Isn’t this place beautiful?” Tails asked. Sonic wrinkled his nose, the fox reeked of gasoline.

A sudden shadow engulfed the boardwalk. Several drops of water sprinkled around them. The air grew heavy and pungent, clinging to their skin with rank breath. Several villagers rushed into their homes, leaving the street barren and littered with overturned barrels and baskets. A child’s toy lay abandoned on the ground. They glanced around in confusion. Previously graceful rays baked them in a sickening green, steel clouds billowing over the horizon and dominating the sky. Below them the waves crashed and foamed rabidly. The wind whipped against them with a stinging bite, a palm leaf pinned against Sonic’s face.

“Where in the world did this come from!” Sonic yelled over the waves. A bolt of lightning struck the water with an ear-popping boom.

“Sonic! Look out!”

Tails jerked Sonic backward just in time. A wooden beam fell from his right, ribbons streaking behind it as it dropped to the ground. Several boards cracked under its impact and fell to the ocean below. A paper lantern ignited a small fire in the wreckage.

“Get to shelter! Hurry!” Sonic shoved them down the street.

“But-Sonic! Wait!”

“No time, Tails!”

The rain came down in sheets, beating against their skulls with hot ferocity. They slipped across slick boards and around the corner to a connecting beach. The sand was already packed with moisture. Through the dense steam and curtain of rain they were met with the stone exterior of a resort hotel, modelled after the ruins. Fighting through heavy tropical plants and up a flight of stone steps they came to a halt under chiselled pillars, hidden from the rain.

“You can stay with us tonight, we can all book a room,” Sonic offered, running a hand through his soaked quills.

Knuckles shrugged.

“I guess I don’t really have a choice.”

\----------

They hadn’t been in the room half an hour and Sonic was already sick of their guest. They were dripping with sweat and suffocated by a blanket of humidity, steam still billowing through the cracked bathroom door after Knuckles used up all the hot water. The AC had also decided to crap out. Sonic rung out his quills with the meanest glare he could muster. His head was killing him. Tails watched him from the window, eyes clouded by churning emotions. He glanced to the desolate jungle and back to Sonic’s pacing form.

“I’m worried about the Tornado, Sonic…”

“Relax Tails!” he snapped. A flash of lightning illuminated Tails’ look of sadness. His expression softened.

“I’m sure it’s fine…”

“It’s out on the beach without a cover, though. I can’t believe I left it there. What if something happens to it?” Tails placed his hand on the glass, fingerprints cutting sharp lines of green into the fog. A part of him was out there in the darkness and the rain, exposed and completely alone...

Knuckles cleared his throat. “Let’s see what’s on.”

Sonic sagged when the news was the first thing to emerge through ashen static.

“Extreme storm warning from six p.m. until twelve a.m., with heavy showers and a tornado watch from seven to nine...” 

Tails’ forehead thumped against the glass when he heard the word “tornado”. The kid was miserable. Sonic rolled his eyes and grabbed for the remote.

“This really isn’t helping. Put on something more－” Knuckles cut him off with a loud “shh”.

“Don’t shh me－”

“Sonic shut up!”

Sonic turned back to the TV and felt a chill twist down his spine.

“I-is that..?”

Knuckles bumped the volume up.

“Reports of a mysterious black hedgehog have sprung up again, this time in Adabat following a series of robberies targeting hospitals and botanical gardens in the United Federation. Notable targets include Frog Forest, Westopolis, Station Square, and Lost Jungle. Citizens are advised to keep their gardens on lockdown.”

Unease buzzed through the room, obnoxious and confused. Knuckles clicked the TV off. 

“Hospitals and botanical gardens… that’s a weird combo.” Sonic mumbled.

“I thought he was dead.” 

“He was…” Tails whispered, his voice dry and cracked. The lights flickered.

Anxiety wormed into their brains. They exchanged glances and fidgeted, rolling the information over in their minds. Tails dropped onto the bed by the window and stretched towards the TV. He had to hear more. 

All they saw was a blizzard of static. They waited. A flash of green followed by a sliver of black. They leaned closer. The static tickled Tails’ nose, half his body teetering over the edge of the bed. The reporter’s Adabatan accent bubbled through the screen as if speaking underwater. The audio crackled and they heard a faint sizzle when - _POP!_ Sparks shot towards Tails’s face. Lightning spliced through the sky and an earthquake of thunder plunged them into darkness. Startled and blind, Tails slipped and face planted into dirty carpet. He dragged himself under the bed, wrapping his tails around his head. Sonic stooped down and peeled the bed curtains back, mumbling words of encouragement.

They settled into the darkness and watched the storm outside. The day felt so blurry and smeared. Tails fidgeted around on the bed next to Sonic and wrapped his hands up in his tails.

“What are we gonna do?”

Knuckles kept his eyes plastered to the floor. Sonic tried to whistle but he sucked at it.

“Maybe we won’t need to do anything. Maybe it’s not Shadow and we’re just pointing fingers,” Sonic said.

“That doesn’t get rid of the hospital robberies,” Knuckles held his hat in his lap, clutching the brim.

“You’re right, that’s serious bad news…” Sonic said.

“It seems suspicious that Shadow shows up with the storm. Something feels off,” Tails said through a yawn.

“We should keep an eye on both him and the weather,” Sonic declared. He slammed a fist into his palm, a flash of lightning illuminating the room.

“Hospital and garden robberies, Shadow’s reappearance, mysterious emerald readings, a monster storm… just what do we have on our hands?” Knuckles shook his head. A few water droplets on his forehead glimmered in the dark.

“I dunno, Knux. I just know it _can’t_ be good,” Sonic said with a sigh.

None of them could shake the feeling that there was more to the situation, but there wasn't really anything they could do about. The sounds of rain beating on the roof lulled them into silence, and much-needed sleep.

Hopefully the AC would kick on by morning.


	3. Calm After the Storm

**Summary for the Chapter:**

> The boys head down to the beach to assess the storm damage and find some fishy business, then Knuckles gets beat up.

They marched down the soggy slope, groggy in the damp dawn. Sonic yawned until his lungs felt sore. His head was still killing him.

“At least the rain cooled things off,” Knuckles said. Tails drooped.

In the distance, towering over a blanket of fog, the sleek shape of the Tornado loomed into view. It looked ancient, possessed by some spirit of decay. Fresh paint which had shone so brightly the day before was now chipped and dull, a husk of its former self in the morning light. A layer of dew shimmered on the surface.

“Oh… no…” Tails whispered, stirring the water in the cockpit with his hand.

“Cheer up, Tails,” Sonic stepped forward. “It won’t take you long to fix it.”

“I don’t know, Sonic…” Tails replied.

“C’mon, buddy! Machines are what you’re best at! You’ll have this fixed in no time!”

Tails shrugged and looked away. He pulled their suitcases out of the plane, water leaking through cracks in the zippers. All the electronics they’d packed were ruined. Tears welled up in his eyes as he kicked the puddle around his feet. Sonic’s heart plummeted into his stomach.

The sun stained the ocean an ominous red, waves bumping gently against jutting sections of rock. It was insane to think the same body battered the land with raw elemental force just a few hours ago…

“Wait a minute…” Knuckles squinted and pointed to the east. “Sonic, wasn’t that rock you were on right there?”

Sonic’s ears pricked.

“What are you talking about?”

“There, where the water’s at. Wasn’t there a rock there?”

He folded his arms and raised an eyebrow.

“Well, actually… No. No, you’re right!” Both eyebrows shot upwards. “The beach can’t get smaller like that. Can it?” 

Tails looked up from the Tornado.

“Huh, the tide rose.”

“That fast?” Knuckles asked.

“Yeah. It’s common for water levels to rise after a storm.”

“But that rock was pretty tall. Could it really have swallowed it up that fast?” Sonic turned to face Tails.

“The rock wasn’t that tall, Sonic. You could dip your feet in the water, after all.”

“Says the shortest one here…”

Knuckles walked towards the water to investigate. The sand was littered with small holes where the rain had fallen.

“It’s like it wasn’t here at all!” he called.

He took a few more steps, the water rising from his ankles, to his shins, to his knees. The water was barley clear enough for him to make out the sand and algae below his feet.

“I’m not seeing any-” his voice cut off, a scream gurgling to the surface in a blast of bubbles. His hat floated where he used to stand. 

He clawed at the water, vision blurred and eyes stinging. It was too dark to see. He kicked his legs as hard as he could, but the weight of his shoes was dragging him into the depths. A flurry of bubbles shot from his mouth. Sudden light blinded him. His head shot through the surface and bobbed along the waves, water slapping against his mouth and nose. His brain pulsed with the sudden intake of oxygen. He tried to call out to the others but he could only gurgle. His lungs burned.

He had just begun to regain his composure when a damp hand grabbed his arm. He splashed and kicked in a panic. The hand gave a yank and pulled him back below the waves. He swung as hard as he could, coming into contact with something sharp. The water was too blurry for him to see his attacker. He fought his way to the surface, only to be pulled back down. The attacker kicked him square in the face. Knuckles’ ears rang.

Everytime Knuckles broke the surface he was dragged back down. He felt himself being pulled down farther with each tug. At this rate he’d hit the ocean floor, the water was swallowing him. He clawed in desperation against what felt like the attacker’s chest. He felt warmth against his face. He was going to be sick.

_Is that pee? Oh god it’s blood. His or mine? His or mine?_

Through the murky water he saw a strand of thick, gelatinous liquid twist up to the surface. It was blood, but the colour wasn’t right. It was green. He wrenched himself free, shooting to the surface and swimming as fast as he could towards land. A hand tugged at his dreads. He jerked away.

He clambered back to shore and sat on the wet sand, attempting to catch his breath. Water sputtered from his mouth as he coughed. He belched. 

“Knuckles what was that? You’re usually such a strong swimmer!” Sonic said. He stood over him, tapping his foot with his arms crossed.

“Sonic shut up you can’t swim at all. You just sink.”

Sonic huffed.

“The ground just kinda dropped,” Knuckles continued.

“Dropped? What do you mean ‘dropped’?” Sonic said.

“For the first few steps it’s normal. Then the ground drops. Just like how it sounds.”

“Did you see the rock?” he asked.

By some miracle, Knuckles’ hat drifted back to the beach. Knuckles scooped it up and dumped the water out before pulling it over his brows.

“Sonic did you not see me get attacked? I had more to worry about than that stupid rock.”

“You were attacked?”

“Yes!”

Sonic stared out at the waves.

“Tails, what do you think?”


	4. Shadow

**Summary for the Chapter:**

> Shadow finally shows up and tension grows.

“Sonic an entire section of ocean floor doesn’t just vanish like that!” Tails’s voice shook as he bounced up the beach, Sonic dragging him by the wrist.

Suddenly, all the warmth was sucked from the air. Tension heavier than any they’d felt last night leaked through their palms in concealed sheets of sweat, clinging to silky gloves with cold, clammy fingers. Shadows fell in saturated blotches over the town. The ocean gleamed oily navy.

The town was utterly ransacked. Thatch roofs lay in shredded puddles along the boardwalk and several planks had been ripped free. Torn fishing nets littered the ground. A row of canoes floated like deadwood in the water, one hull dragged up into a splintered heap on the street. Families lined the wreckage in despair.

A disgusting smell wafted through the air. Hundreds of dead fish and other sea life littered the ground, some still flopping against the damp boards. There goes breakfast.

Tails held his hand over his nose. Sonic came to an abrupt stop and Tails slammed into his spines, a cry of surprise muffled by Sonic’s shoulder blades.

Stunned, the group followed Sonic’s gaze to the end of the boardwalk where a line of jungle flora grew in broken, storm-battered tangles. They could hear each others’ breathing.

“Shadow?” Sonic stepped forward. Tails slid off his spines.

He strained his eyes, and caught saw a streak of red tucked into the overgrown shadows. Shadow really didn’t look the way he thought he would; a little lankier and shorter, and barely visible through the creeping fog. He still wore gaudy bracelets.

With a wave of his hand, Shadow disappeared into the vibrant shade of the jungle. A faint gleam of gold through thick underbrush. Sonic blasted after him, blue streak rupturing the town. Debris blew in all directions, and as soon as he had set off, he was gone.

**Notes for the Chapter:**

> Super short because I forgot to update a few times. I have no schedule.


	5. Jungle Joyride

**Summary for the Chapter:**

> Shadow finally shows up and has a chat with Sonic. Only after a classic chase scene, of course.

Sonic charged down the boardwalk.

The ruined huts faded into muddy blurs as he dipped into the jungle. Morning sun sliced through the trees, speckling the ground with bloody rays of light. His feet beat up clouds of dust. Distant bird cries echoed all around him, screeches dissipating in the canopy. Shadow was nowhere in sight.

He tripped and knocked his teeth on a rock, a vine woven tight around his shoe. He could feel the circulation being cut off. He twisted and jerked. Almost free. He crawled an inch forward and yanked his foot. He felt the vine give way when--his body shot fifty feet in the air! He screamed, swinging upside down towards an enormous tree. His quills sank into the wood and slid down the trunk. His legs flopped over his head and somersaulted him onto his back. What a pretty morning sky...

He craned his sore neck and rose slowly. His eyes adjusted to the darkness. A figure dashed along the branch up ahead, glimmers of gold telling him exactly who it was.

“Shadow! Wait!”

He scrambled to his feet and slipped, body twirling through the air. He hit the branch below with a sickening crunch.

“Where are you going? Stop!” he held his nose in his hands.

Shadow glanced over his shoulder with empty eyes. Sonic’s head drew back a little, shoulders stiff.

The jungle twisted in arching tints of shadowy greens and browns. Branches weighed with tropical leaves blended into their peripherals. 

Rich palm leaves slapped against Sonic’s face. Bark shook to the ground, clouds of dust billowing around his legs as his feet beat harder and faster against the trees. He leapt over vines. Mowed down bird nests. Adrenaline burned in his veins. Farther ahead Shadow’s blurred shape blended with the darkness of the trees. Sonic followed the flashes of gold.

A barrage of sound flooded his ears. It sounded like a herd of horses, galloping over the forest floor. A cool spray of moist air covered his face. The branches began to taper. They grew more and more brittle the farther he went, and no matter how many times he switched they became progressively thinner. He gasped. The tree gave out beneath him, and roaring below was a great pool of swirling white water. He rolled in midair and grabbed a branch. His fingers slipped. He dropped hard and landed on a jutting piece of rock with a splat. The surface was slick and cold. He lifted his face off a coat of yellow lichen and gazed around.

The pool sat in the center of a large rock crescent, surrounded by a half circle of smooth cliffs and overhanging trees. Over the roar of water he could hear Shadow’s shoes hissing across stone platforms. He vanished through a curtain of mist. Sonic peeled himself off the rock and flung back into pursuit. He could feel the soles of his shoes sliding dangerously close to the edge of the rocks. Every jump made his heart race. His palms were drenched with cold sweat. His brain pounded against his forehead until he felt his head was going to split open. A migraine surged through every tissue, his nerves on fire.

He landed on the other side and let out a gasp of relief. He was safe. 

Frustration boiled in his temples. This game of tag sucked hard, and he was tired of being ignored. He hardly noticed the warm stream of blood bubbling against his lips.

He broke onto the beach and glanced around, hesitating in the waning jungle shade. Far to his right he saw him, slouched against the trunk of a palm tree. Shadow. He acted as if Sonic wasn’t even there. Sonic couldn’t believe it. He wasn’t some trick of the light, or surprise new face, he was Shadow. A part of him still wanted to deny his existence, still had to deny his existence. The shock would be too much otherwise.

He rubbed his eyes, grinding to a halt beside Shadow and staring him up and down. No matter how many double takes he made, that was still Shadow standing there. He kept his expression confident. He had no way of knowing what was going through Shadow’s mind. Even if he did know, he was certain Shadow was up to no good. He tapped his foot, a cloud of sand billowing around them.

“Shadow what is your problem? You have a lot of explaining to do!” he said. His mouth tasted horrible.

He went to say something more but was taken aback, breath caught in his chest. Something was off about Shadow’s appearance. A semblance of rib jutted through a gap in his spidery arms, muzzle looking a little green. Shadow turned away, sensing his critiques.

“The ruins…” Shadow mumbled. One of Sonic’s ears perked up.

“What are you talking about?”

Shadow held a hand out to the sea.

“Adabat is famous for its ancient ruins, it’s a selling point,” he said. The palm tree cast a shadow over his vague expression.

“So? I don’t care about the ruins right now. Where did you go? Why are you here? What’s up with the robberies?”

Shadow’s gaze slid toward him and froze. His eyes stretched wide as moons.

“Wh-what?” Sonic asked. The hint of anxiety in his tone hardened into irritation. Shadow’s weirder than before.

Shadow turned towards him, slow and calculated. Sonic’s spine tingled. He shuddered, feeling Shadow’s gaze creep up and down his body. His eyes were sunken. They glowed from within shadowy pits in his face, black pupils piercing his soul from uncanny irises.

“Sensitive subject, huh?” he ran a hand over his mouth, shocked to find it bloodstained. “No big deal, I didn’t think you’d want to talk anyway.”

“Then why did you follow me here?” Shadow sounded more annoyed than confused. Their eyes locked together. Tension buzzed between them. Shadow took a step forward, Sonic took a step back.

“I don’t know if you’ve noticed Shadow, but you’re weird. Really weird...” he paused. “Are you okay?”

His back slammed into another palm tree, head hitting the trunk. A leaf fluttered to the ground between them.

“I don’t have to explain anything to you. My whereabouts are not important.” Shadow closed his eyes and sighed through his nose.

“Does it not strike you as odd that the ruins have vanished?”

Sonic shrugged.

“I… guess I never noticed,” he said. Something about him being here felt so wrong. Like he was trespassing. Shadow’s gaze slid back towards him, and the unease bubbled into nausea.

“Why do you care so much about the ruins anyway? Do they have something to do with－”

“No. No they do not,” Shadow interrupted. “I’m appalled you don’t feel the changes in the world.”

“Am I supposed to..?”

Shadow rolled his eyes.

A few moments passed. Navy waves crashed against the beach, their roars lifting the silence between the two hedgehogs. After an awkward amount of eye contact, Sonic dug his toe into the sand and attempted to whistle. He still couldn’t do it.

“Shadow I… think I’m gonna go. It’s was nice seeing you, kinda. I was hoping you’d tell me about what happened in the U.F., where you’ve been in the past year. I guess not though…” he turned away, disappointed that he’d trailed Shadow all the way here for nothing. Shadow obviously wasn’t willing to talk, and he didn’t want to fight him again. He’d be better off keeping an eye on him while he went about his vacation. Maybe this whole thing was just another misunderstanding.

“Oh, one more thing. Wipe that blood off your face. It’s really distracting.

Sonic turned back in shock. He had no idea he’d been bleeding _that_ badly. Shadow had his back to him, dark quills blowing in the salty breeze. His arms were still crossed, and once again it was as if Sonic wasn’t there.

Sonic’s face felt sticky. He wiped a crust of blood from the corner of his mouth, and headed back to Seaside Town.


	6. Shady Sands

**Summary for the Chapter:**

> Sonic returns to the hotel with no leads on Shadow's motives. While looking on the beach for clues, he and the gang come across some evidence of Eggman's schemes and their suspicions continue to rise.

Tails and Knuckles were waiting for Sonic when he emerged from the jungle.

"Took you long enough," Knuckles said. He gasped when he saw the blood covering Sonic's face.

"Sonic! What happened?" Tails cried.

"Relax, Tails. Just got a little scraped," Sonic said. He brushed the dirt off his arms and cracked a smile.

"A little goes a long way…" Knuckles muttered.

The two chaperoned Sonic back to the hotel room so he could wash up. The hotel itself was miraculously untouched, the only signs of the storm being a couple branches and leaves scattered on the stone stairs. Once inside, Sonic stared at himself in the mirror. His face really was covered in blood. Most of it had already oxidized, dried on his face in hard, brown crusts. Disgusting. He kept the faucet running while he wiped his face with a wet washcloth. The rough fabric felt warm and comforting.

As he scrubbed his mind ran over what Shadow said. All that bark and no bite was definitely typical, but the talk about "changes" in the world really bugged him. It probably had something to do with the storm, and that missing chunk of beach, but how would Shadow know anything about those? He should've asked more questions. What if Shadow was trying to tell him something? To actually help him for once? Then again, that was definitely not typical of Shadow. He wouldn't help him without a bribe, or the fate of Maria's memory at stake. Still, if something really was going on on the island, and Shadow knew something about it… He had to get to the bottom of this…

A knock at the door interrupted his thoughts

"Sonic?"

"Yes, Tails?"

"Knuckles and I are heading back to the beach, you wanna come?"

_The beach would be a perfect place to sniff out more clues!_

"Yep! Just a minute!"

The stretch of beach seemed so open now. Every footprint, every overturned rock, was a vital piece of the puzzle. Sonic's gaze swept through the sand, eyes peeled for any footprints that might belong to Shadow, or even Eggman.

Tails circled the plane. His eyes scrunched, fingers curled around his chin. He pulled soaked luggage and clothing from the cockpit and dropped them on the beach. Placing two hands on the plane's side, he pushed with all his strength. His tails spun wildly, propelling him forward and shoving harder into the plane. It still didn't budge. Sonic watched from across the beach, chuckling softly. After several minutes of fighting, Tails' heaves and grunts slowed to tired pants and he dropped to the sand.

"Hey! Over here!" Knuckles yelled. He was bent over a mass of mechanical scraps, hand waving violently over his head. Sonic and Tails exchanged glances before heading over to investigate.

They gasped. The crushed body of some badnik lay half-buried in the sand, rendered unrecognisable by all the damage. Farther along the beach an enormous metal sphere protruded from the rocks.

"What in the world is that?" Sonic asked. He stepped forward to take a look. The sphere dropped from the rocks and hit the ground with a clatter, Sonic leaping backwards and barely avoiding being squashed. It rolled a few feet and lay still.

"That's Eggman's hover-machine-thing!" Tails said. "It seems to be in pretty good shape, he couldn't have been flying it out in that storm. Especially not since it's made of metal…"

"Then, how'd it get here?" Knuckles asked.

"It wasn't here yesterday," Sonic added.

"That applies to the badnik, too. How'd that get beat up so bad while the hovercraft is fine?" Tails said, scratching behind his ear.

They thought for a moment, a few ideas bouncing around. None of them seemed plausible. After much grunting and head scratching and shrugging, Tails approached the craft.

"Wait a second… this isn't Eggman's hovercraft, it's some kind of… submarine thing?"

"Huh?" Sonic circled the vehicle.

"Look, propellers!"

Two small blades jutted from the back of the machine. Tails managed to get one spinning with his hands, a small whirring sound filling their ears.

"Knuckles, try to get this thing in the water," he said.

Knuckles gave it a push. The sphere rocked a little, nearly tipping into motion. It dropped to the sand with a thud. He tried again, pushing the sphere towards the water and letting it balance itself on the surface. The craft bobbed in what used to be the shallows, the trio watching it diligently. It rocked, sending waves in folds over the beach. Then it flipped over.

"Knuckles! Knuckles flip it over!" Tails screamed.

"I'm… trying!" Knuckles said, parrying the craft. It began to fill with water and sink.

"Knuckles no!"

Knuckles threw his hat at Tails, vanishing beneath the water. The craft's side was barely visible now. It sank a little deeper, then leapt from the water. It fell back to the surface and sprayed Tails before laying still. Knuckles emerged from below and tipped the water from the cockpit. He held the craft steady in his arms.

Tails took a deep breath, "Ok. Now we know this thing has to be weighed down otherwise it'll tip."

He shook his fur out, showering Sonic in droplets. Hovering over the craft, he gently placed himself in the cockpit and began to experiment with the buttons. None of them worked.

"Oh come on!" Sonic exclaimed. "This thing is useless!"

Tails hummed and pressed an over sized red button, hoping for better results. The craft lurched forward, slamming into the beach with a massive drill. The entire vehicle vibrated, nearly throwing Tails out as it carved into the land with incredible force. Tails hit the button again and the craft settled down, the drill vanishing into the front of the craft. Sonic's eyes were stretched wide.

"Impeccable timing. Eggman was definitely responsible for the missing chunk of ocean floor. What else would that drill be for?" Tails said. The only other button that worked pulled a bubble over the cockpit, the rest either waterlogged or jammed.

Knuckles pulled himself back onto the beach and stared out at the ocean.

"Whatever he's doing down there, he's nearby. I think he's causing the strange readings in the master emerald, too."

"What makes you think that?" Sonic asked. He helped Tails pull the craft onto the sand and stared at Knuckles.

"I have a feeling…"

Sonic rolled his eyes. "You're probably onto something. He's _always_ the one messing with the master emerald."

"We gotta hide this thing somewhere. If Eggman's close, we can't let him get his machine back," Tails said, dusting his hands off. "Let's put it in the jungle. I think we can scavenge the parts."

The three heaved the sphere into the shade and dug a small trench, rolling it into the sand and placing a layer of leaves on top. They smeared wet sand over the metallic surface just in case Eggman could see the glare through the canopy. The sun was already beginning to set, twilight splashing onto the beach. The air grew cooler with the crescendo of insect chirps winding through the jungle. Despite the unease hanging over them, the waves and the intricate tangles of jungle were so peaceful, tied together by cobalt shadows pooled in the sand. Music flowed from the village nearby, signifying that everything would be okay.

They shared a glance, and retreated back to the hotel.


	7. Mottled Shadow

**Summary for the Chapter:**

> Sonic crash lands in the jungle and pursues a mysterious trail of seeds into the Gaia Temple, one of seven in the world. What started as diplomacy turns into a disgusted retreat

**Notes for the Chapter:**

> Warning: This chapter contains vomiting.

The next morning was hot and muggy. Jungle fronds glistened in the young yellow light, dew dripping to the damp ground. A suffocating level of moisture made their noses precipitate as they fought their way through the underbrush. Sweat seeped from their pores.

“Tails where'd you put that thing?” Sonic grunted, swatting at a cloud of insects.

“It’s not far.”

The jungle seemed to stretch for miles. Steam billowed through the air, coating their skin in a damp, sticky sensation. Finally a dull metal gleam broke the endless sea of green. Tails ran forward to clean the surface. He tugged at the craft but couldn’t get it to budge.

“Knuckles! Hey!” Tails yelled. “Sonic, where’s Knuckles?”

Sonic looked around. “Uh… I don’t know. He’s probably still asleep,”

Tails yanked the craft out of the trench, falling over backwards in the process. He vanished behind a group of ferns, heading towards the beach. Sonic sighed. The thick trees towering over him shrouded him in darkness. He felt so… small. He dragged his foot over the craft’s side, toe tapping against the hot surface. He was bored, and sticking around to watch Tails tinker sounded like torture. Going back to the hotel to retrieve Knuckles would be useless now, he’d probably gone off to look for evidence to back up his “feeling.” He mentioned a power ring or something, what was that about? Sonic groaned and gave the craft a kick, stubbing his toe. His foot flew up into his arms. He cradled it and hopped on one foot, desperately trying to plant his remaining foot in the dirt for balance. He hopped a few inches forward and tripped on a vine, falling head-over-heels into the darkness of the jungle. He bounced down a small hill at an impossible speed, body a blur as he curled into a ball and bumped over the rocks. He hit the bottom with a dull thud and lay still. He pulled his quills out of the ground, cupping his shoulder in his palm. If he didn’t know any better, he’d think he traveled back in time. He sat in the centre of a small clearing, whole body aching. His eye fell on a curious mound of dirt. Scooting closer, he squinted to see what it was through mottled shadow.

A seed protruded from the top, shell splitting to reveal green strands of growth. He looked ahead and found a cluster of similar mounds, each roughly five inches apart. Almost like footprints. He followed them deeper into the trees, ears held alert. To his left came a rustle in the bushes. He pivoted in one swift turn, fists clenched, eyes scouring the underbrush. He heard it again, this time to his right, and whipped around. He jumped as a flash of black shot from the bush. It homed in on him like a missile before sharply pulling into the canopy, a single leaf falling to his face. _Just a bird._

He slapped himself. Wussing out in a place like this was ridiculous. The Adabatans had lived here for generations with no trouble. The only things he had to worry about in this jungle were natural flora and fauna. Nothing he couldn’t handle.

He pressed on. The mounds began spacing out, growing from five inches apart, to seven, to nine, to a foot. Sonic found himself on his hands and knees, fingers clawing through the jungle floor in search of more mounds. Eventually he heard the gurgle of a small stream, and fought through a cluster of ferns onto its bank. Sunlight glittered on the quivering surface. His eyes burned.

He paused for a while and rested at the water’s edge. The water was cool against his sweaty hands, washing clumps of dirt out of the seams of his gloves. Too bad he’d never get the stains out. He splashed the water against his face and let it drip down his neck, clouds of steam billowing off him. The sunlight had already saturated from a pastel yellow into a harsher white, falling in beams all around him. His stomach growled.

He stood slowly and stretched, walking through the stream to the opposite side. The mounds had also crossed over, now becoming increasingly smaller the farther they stretched out. The hair on the back of his neck bristled. He’d forgotten all about Shadow. Alone, on the bank of some stream, he was open, vulnerable. And possibly hot on his trail. Talking to Shadow sounded like worse torture than watching Tails tinker on that machine. From what he saw last time, Shadow was familiar with this jungle. It was entirely possible he had been here this whole time, even during the ambiguous period following his “death." Maybe he survived the fall and landed in Adabat, never bothering to seek anyone out or escape the cluster of islands. Ultimately it didn’t matter. Shadow was creepy, even before he “died." Sonic knew deep down that the best way to sort out the freaky news report and Shadow’s disappearance was to actually ask Shadow, he just didn’t feel like it. It was his vacation, and he was off duty. Someone else can do the hero stuff while he’s taking down time. Someone like Knuckles. Knuckles never seemed too busy, why didn’t he try being the hero for once?

He wiped a bead of sweat from his brow and set off at a brisk power walk down the stream. It was a little slow for him, but he could use some thinking time. It wouldn’t hurt to keep an eye out for Shadow, either. He flicked a rock with the tip of his shoe and watched it bounce across the stream. It landed on the other side with a click, disappearing into the identical masses of pebbles. His ear flicked irritably at the touch of a mosquito.

Shadow’s reappearance was confusing and strangely ominous, but the thing that really bothered him was how he felt about it. He didn’t know how he felt at all. Shadow was never his friend or ally, but it was kinda nice to know he made it out alive. He didn’t exactly deserve to die. He didn’t think. Even worse than that was the trouble Shadow could possibly bring. He probably robbed those hospitals and stuff, his sightings can’t be a coincidence, and the reporter specifically said “again," implying Shadow’s been busy. But that conflicts with his theory about Shadow landing in Adabat. How'd he get to the United Federation without them finding out? And why would he rob a place like that? What could he possibly need from a hospital? If he was hurt from the fall, he wouldn't need to resort to robbery to heal his wounds, right?

He sighed. All his explanations seemed like excuses. Just a bunch of maybe’s on a vacation that quickly turned from refreshing to rabid. Why did everything have to hit the fan when he was around? It didn’t matter what he was doing or where he was going, all the conflict revolved around him. Couldn’t someone else deal with the chaos for once? This vacation had seemed so good, but already by the end of his first day things had begun to go downhill. It started with the storm, then Shadow, then Eggman’s trash on the beach, and now he was consumed by curiosity and frustration. He’d have to do something about all this, whether he liked it or not.

The stream blossomed into a sparkling pool, trails of water flowing through cracks in the cobbles of some ancient temple. Sonic gazed up at the structure. How long had he been walking?

A layer of moss coated almost everything, clashing with the creamy white of timeless stone. Vines dangled all around him. From within the temple beams of sunlight danced in the dusty air, and littered the ground with soft spots of yellow. The whole structure glowed. He pulled himself to the entrance and stared back out at the jungle. It looked ominous from where he stood - it was watching him. He shrugged and stepped inside, drawn to the temple like a magnet. What did Tails say this place was called? It’s was in the flier… Gaia Temple! It was the Gaia Temple, one of seven in the world. Ornate carvings wrapped around giant pillars and twisted through the temple chamber. Very intricate.

He was glad he’d taken today slow. He hadn’t gotten anything done, and he’d spent more time glancing over his shoulder than he had relaxing, but something about this place put his mind at rest. It was so beautiful. He paused to trace his fingers over the ridges of a prophetic inscription, feeling the sharp edge of a chaos emerald and a groove of light in the stone. His ear flicked. He could hear something in the shadows. It surrounded him, echo hovering everywhere.

“Sonic.”

A voice, dead and weak, was delivered from darkness. He jumped, dust swirling around his ankles.

“Shadow?

There he was. Speak of the devil. His form obscured the light leaking in through the temple arch, casting a ghostly shadow between them. It stretched towards him as Shadow began to approach.

“Why are you here? Where have you been?” Sonic asked. That caution bubbled up again, as if he weren’t meant to be here.

“I could ask you the same thing.”

This time Sonic didn’t back down. He had questions, and they _would_ be answered. He took a strong step forward, posture assertive and bold. Shadow raised an eyebrow.

“I asked you first,” Sonic said. His voice struggled to stay steady. Something about Shadow sent his skin crawling.

“If you really must know, I've been staying here,” Shadow replied, checking his nails despite wearing gloves. Sonic felt sick, he could see his finger bones through the fabric. He smirked anyway.

“Why would you wanna live in a place like this? Wouldn’t a cave suit you better?”

“Your first reaction to seeing someone who’s been dead for years is to start cracking jokes. Typical.”

“What’s that supposed to— I mean, Hey! Don’t change the subject. I know you’re up to no good Shadow, don’t even try to lie to me.”

Shadow looked as if that was the funniest thing he’d heard in days.

“Sonic what on earth are you talking about?”

“You know! The hospitals, the robberies, being… alive!” Sonic said, gesticulating his hands into a tangle.

“Keep your voice down, I have a headache.”

Shadow pressed his ears into his head, fingers rubbing the space between his eyebrows. He looked up, feeling incredibly woozy. The room began to wobble, like it was submerged underwater. Shades of green and black blotted out the light in the world, folding together into swirling clouds. He swayed on his feet. A shot of electricity and a quaking wave of nausea sent him hurling forward with a cry, reaching out to stabilise himself on a pillar. Sonic, seeing this as an attack, landed a swift kick right in his face. His head snapped back. Unable to see and struggling for balance, he collapsed to his knees in the dust. Sonic watched, eyes glittering in the light. Shadow’s body jerked horrifically. His skin rippled, shivering along the arc of his spine. He threw a hand up to his mouth but it was no use - a waterfall of green fluid flowed from his throat and splashed to the floor. He gurgled in anguish. Spewing from his gaping mouth came more acidic liquid, a vine of green, seaweed-coloured ooze snaking through his teeth. Clots of red pimpled the bubbling goo. A burning stench pierced the air.

Sonic gagged. Every time he opened his mouth he could taste the fumes of ungodly funk.

Shadow looked up at him with hollow eyes. He clutched at his throat and attempted to stand, shaking violently as he grappled his way along a pillar. Sonic wasn’t sure if he wanted to help him or keep his distance. He took a step forward but noticed a particularly disturbing feature: Shadow’s veins. They twisted along the base of his neck, wrapping around his jaw and clenching his muzzle, pulsing beneath the skin. A soft emerald glow permeated the surrounding darkness.

Sonic stepped around him in a half circle, spines bent against smooth temple wall. Shadow never dropped his dull stare. His bony fingers stretched out with a disgusting _pop._ Sonic shuffled faster along the wall.

Shadow’s eyes seemed darker. The bags a little heavier. He uttered a faint hiss.

“Shadow?” Sonic choked. “Look, I, um…”

Shadow’s expression was unreadable. Desperate? Scared? ...Predatory?

**Squelch.**

Sonic’s foot sank into a squishy section of floor. It flew out from under him and sent his leg high into the air, the rest of his body struggling for balance. He crashed into a pillar. Cold backsplash on his leg tied his heart into a knot.

Sonic sped off. No goodbyes, no forethought, no questions answered. Only quivering nausea.


	8. Finally, Some Good News

**Summary for the Chapter:**

> Sonic rushes back to tell Tails what happened. Fortunately, something good happens for once.

Tails hammered away at the Tornado. His back was sore and every inch of his flesh burned in the sunshine, but it was so worth it. The new coat of paint beamed up at him, and as he turned in the last screw and wiped a bead of sweat from his brow, he stepped back to admire his work.

 

_ Awesome. _

 

A rumble like thunder erupted from the jungle to his right, the ground vibrating beneath his feet. His head whipped around just in time to see Sonic’s blurry outline come crashing along the beach. His face was contorted in panic, and his eyes were brimming with something so incredibly unlike Sonic. Was that shock?  _ Fear? _

 

A cloud of sand shot up in his face as Sonic screeched to a halt. His muzzle was flushed in the midday light. He bent over and placed his hands on his knees, chest heaving with wheezes.

 

“Sonic? What’s the matter with you?” Tails asked.

 

“I-I saw Shadow! In the jungle! He was weird, and he puked, and it was gross, and I... I stepped in it!” Sonic cried.

 

Tails raised an eyebrow. How do you respond to that?

 

“Uh… start from the beginning?” Tails asked. He pulled himself onto one of the plane’s wings and stared down at Sonic.

 

“Ok. So,I went for a walk, and I found these mounds in the dirt.”

 

“Mounds?”

 

“Yeah. Mounds of dirt. Some of them had seeds in them. Anyway, I followed the mounds and I started thinking about what’s been going on, Shadow’s whole not being dead thing and stuff. And then I found this temple.”

 

“Oh! You mean the gaia temple!” Tails perked up.

 

“Sure. I went inside, and a few moments later, there’s Shadow. I tried to ask him some questions, but then the worst thing happened. He puked,” Sonic said, sticking out his tongue.

 

“Oooooh!” Tails mocked.

 

“This is serious! It was green, and red, and Shadow’s veins were… they were bulging. Pulsing and glowing kinda green.”

 

“Wait, slow down. Describe him in full detail please,” Tails hopped down from the wing and dug around in the cockpit, revealing a small notebook and a pen. He leaned towards Sonic.

 

“Well, he seemed fine at first, but then he collapsed onto his knees. And his skin started... rippling.”

 

“Rippling?”

 

“Yeah. Like something was under his skin. Then he puked, and it smelled awful. Then I noticed the veins.”

 

“Were they glowing like that when he came in?”

 

“I don’t know. I wasn’t paying attention to them until he started puking…” Sonic said. He puffed out his cheeks as if holding back his own puke.

 

“Give me your shoe,” Tails put his notebook down and held out his hand.

 

“What? Ew, why?”

 

“I want to see if there are any samples on the sole.”

 

Sonic reluctantly tossed him the shoe. Tails nearly dropped it, glaring as he set it down and pulled a cotton swab out of his toolbox. His nose crinkled at the green slime still wedged into the ridges. It smelled like death and fertiliser. He ran the swab over the shoe and tossed it back over his shoulder. Placing the swab in a glass slide, he peeled off his glove and turned to face Sonic.

 

“This is just a temporary container until I can recover my lab stuff. I’d love to run some tests on this.”

 

“Didn’t your equipment get destroyed in the storm?”

 

“Shoot!”

 

Tails puffed out his cheeks. He crossed his arms, the slide reflecting blinding sunlight into Sonic’s eyes.

 

“Well, the microscope and basic materials were in a pretty tight container, so if we’re lucky they’ll only be wet. Can’t say the same about the electronics, though…”

 

Sonic was exasperated. All he wanted to do was relax.

 

“Let’s just chill Tails, we’re on vacation. We can check on that stuff once we get home.”

 

“Sonic you know this is starting to get serious. We have to take action. You think so, too, otherwise you wouldn’t have thought so hard about Shadow. If we ignore this who knows what could be going on right as we speak.”

 

Sonic nodded.

 

“You’re right. I don’t think Shadow’s the only one we have to worry about.”

 

Tails’ face lit up, tails fluttering behind him. “It’s not all bad, though. Check out the Tornado!”

 

Sonic hadn’t even noticed the new makeover. The paint was restored to its glossy glory, the cockpit bone dry and ready for flight. It shimmered in the sun.

 

“Woah, Tails! How’d you do this?” Sonic said with a laugh.

 

“I have my ways. You haven’t even seen the best part.”

 

He lowered himself into the cockpit. With the touch of a button the plane rumbled with familiar gusto into the battle mode’s bullet shape, this time a little rounder around the edges. The wings folded into the side, two small propellers emerging from under the plane. With a whir a glass bubble enclosed the cockpit and headlights sprung out the front. Tails pressed his hands against the glass, waving to Sonic. He pressed the button again, and just as quickly as it had transformed the plane morphed back into its normal shape. It was like magic.

 

Sonic was speechless. Tails laughed and dropped to the sand beside him, looking up at him for approval.

 

“I had blueprints for a boat upgrade in my suitcase, I think I mentioned it the day before yesterday. I didn’t have the necessary parts to make a separate upgrade, so I just converted the battle plane into a submarine.”

 

“But, where’d you get the parts for that?”

 

“None of this would have been possible without Eggman. That’s something I never thought I’d say.”

 

Sonic laughed. “What would I do without you?”

 

Tails shrugged. “It’s nothing, really. Anyways, let’s go find Knuckles. I’m sure he’d want to see what we did with the plane.”

 

“Right.”


	9. Bubble

**Summary for the Chapter:**

> Tails shows off the submarine in action, while Sonic and Knuckles cat fight in the backseat.

They found Knuckles in Seaside Town, attempting to re-thatch roofs with the villagers. They each grabbed him by an arm and dragged him back to the beach, eager to hear what he had to say about their new submarine.

 

He held the brim of his hat with his hand and nodded his approval. “Nice job fixing this thing up, Tails. That didn’t take you long.”

 

Tails ran through another lecture about the capabilities of the new and improved “Tornado-2” and pressed the transform button, just as giddy as he was the first time. Knuckles watched in awe.

 

“Pretty rad, huh, Knux?” Sonic said. He slung an arm over Knuckle’s shoulders and dropped his weight to one side. He stood like a wall, not even leaning under him.

 

They helped push the Tornado into the water and clambered into the cockpit with Tails. Squashed into a knot of limbs and flesh, Knuckles pushed Sonic’s cheek into the bubble as he tried to adjust. Tails elbowed them every time he pressed a button or shifted gear. He tilted his head up to set the GPS and bonked Knuckles right in the nose. The tears welling in the corners of his eyes made Sonic laugh, one particularly loud guffaw cut off by Tails’ tails swiping across his face.

 

“This sucks! I can barely breathe,” Sonic choked, neck straining to keep his head over the tails.

 

“Oh come on, we haven’t even gone under yet!” Tails said.

 

The sub dunked below the water. Slowly the shades of blue darkened until they were hovering above the ocean floor, surface glittering on the sand. Tails pushed the gearshift forward and they lurched into motion. The water around them was crystal clear, air bubbles swirling past their propellers. The ocean sprawled for miles. Sonic didn’t mind his face being pressed into the glass anymore, it felt good against his cheek compared to the stuffy state of the cockpit. He watched as the craft drifted along the current, passing a city of coral and sea life. Fish wove in and out of kelp beds, crabs and snails clung to the rocks, the biggest turtle he had ever seen floated past. 

 

They twisted through the coral beds. Knuckles kicked him in the back of the leg.

 

“Knuckles!”

 

“I’m trying to adjust calm down!”

 

Tails didn’t see the point in yelling at them and just let them bicker. Knuckles threw a backhand at Sonic but hit the glass instead, the quill on Sonic’s back catching the cuff of his glove and popping his fingers against the glass. Tails ducked to avoid Sonic’s knee. Knuckles drew back to throw another slap but halted, one hand smashing Sonic’s head against the glass.

 

A cloud of sand fogged up their view. Through the haze Sonic could make out the shapes of worn columns and ancient stone. The sub drifted through a maze of brilliant white. Columns stretched towards the surface like giant kelp plants, aquamarine waves quivering on their surface.

 

“Woah…”

 

Tails laughed. They twirled through an ornate carved archway into the remains of another temple. The ruins were very narrow. Crumbled staircases and broken pots lined the ground, a couple stone pyres breaking through the surface. Statues of long forgotten people sat in eternal meditation.

 

“Hey the villagers were talking about this. It’s some kinda old village,” Knuckles said.

 

Fish swam in and out of the old doorways. Sonic swore he saw eyes peering at him through a window but he brushed it off. The same turtle paddled towards them from the darkness, and Sonic noticed the garden of plants growing on its back. They fluttered behind it like flowing strands of green hair, vibrant orange starfish clinging to its shell. Its dark eyes shot them with a deep stare. That turtle had probably been around since this village was new.

 

Tails guided the craft out of the temple and floated to the surface. He lowered the bubble and they gasped for breath, the salty breeze a great relief. They bobbed along the waves and stared at the rocky buildings sitting in the water around them. Knuckles reached out and brushed a hand against one.

 

“Well, what’d you guys think?” Tails asked.

 

“The cockpit’s a little small… and could use a little less Knuckles,” Sonic replied. Knuckles grunted.

 

“It’d smell a lot better if Sonic wasn’t here…”

  
“No, I mean about the actual submarine experience,” Tails cut in

 

“My points still stand,” Sonic laughed. Knuckles punched him in the arm and he almost fell out the side.

 

Tails rolled his eyes and started back for shore. He was scared to raise the bubble lest they start fighting again.

 

“Oh, before I forget, help me get this thing to safety when we get back to shore. I’d hate to start all over.”

 

“Sure thing, Tails!” they replied, almost in unison

 

The rest of the trip was completely silent. They hid the submarine in the jungle just as the sun began to set, and hurried back to the hotel. As they speed walked down the boardwalk, Knuckles held his head. Sonic and Tails laughed and chatted, but he kept his lips sealed. His dreads obscured his expression.

 

“Knuckles, are you ok?” Tails asked. They paused on the stairs to the hotel in a cluster.

 

“I just feel so anxious, but I don’t know why,” he replied, staring at his hands. “I feel static in the air. Something isn’t right.”

 

“Does it have to do with the chaos emeralds?” Sonic asked.

 

“Almost, but not quite. I feel another presence.”

 

“Presence?”

 

“It’s when you can feel someone else is nearby, Sonic,” Tails said.

 

“I know what it means. What creeps me out is that Knuckles is sensing this after those Shadow encounters.”

 

“You’re right. He and Dr. Eggman are our primary suspects for shady business right now. We know they're here, and Shadow knows we're here, but that doesn't account for Eggman...” Tails’s voice trailed into a murmur. He pulled them closer. “You don’t think they’re watching us, do you?”

 

The air tingled with unease. Tails bit his lip and glanced from one to the other. The palm tree shadows stretched over them and cast the stairs in twilight, the last of the sunlight dipping below the waves. A cool breeze blew through the leaves. Knuckles shook his head and pulled away, pushing his dreads out of his eyes.

 

“Let’s keep an eye out, just in case you’re right.”

 

Sonic and Tails nodded. They walked quietly back to the room and pushed their beds a little closer together for emotional support. They left the window cracked half an inch for some blessed fresh air. No way were they going to spend all afternoon in a stuffy cockpit just to be broiled in their room. As the jungle began to swell with the symphony of insects, they drifted off to sleep.


	10. Dark Waters

**Summary for the Chapter:**

> A mysterious tunnel is discovered in the ruins, along with some suspicious machinery. Just what is Eggman up to?

“Knuckles you’re looking rough. You sleep okay?” Sonic asked. He stopped pushing the Tornado and rubbed his eyes, his words lagging into a yawn.

 

“Fine.”

 

Knuckles’s dreads clung in tangles to his scalp, his hair tie having disappeared in the night. Normally he’d have blamed Sonic for his loss, but he couldn’t even walk straight this morning. One bloodshot eye glanced at Sonic. “Too heavy?”

 

“Naw, I’m good.”

 

Tails motioned for them to stop and walked around to the other side.

 

“Alright, guys. I know the cockpit is small and uncomfortable, but we gotta cooperate this time. If you keep fighting you might break the glass, I found a little crack in it.”

 

“How do you know we did that? We got that thing from Eggman, maybe he made it.”

 

“Sonic we can’t take any chances.”

 

\----------

 

They circled the ruins, Tails snapping photos using a disposable camera. To Sonic’s left Knuckles sat in silence, barely moving even when Tails’ tails slapped against his face. Sonic could feel his pulse against his leg; slow, steady, and weak.

 

“Hey, are you doing okay?” he leaned forwards to get a better look at his face.

 

“Why?”

 

“You look dead today.”

 

“I just… I’m just worried about the energy readings in this area. They’re flaring really bad. Something’s wrong.”

 

“Well, like what?”

 

“I don’t know how to explain it, I gue—” Tails cut him off, “Hey, check this out.”

 

He pointed towards the other end of the ruins. A long metallic beam protruded from the rocks, bubbles shooting everywhere. Groups of similar structures surrounded the entire area, along with enormous holes in the coral. Pebbles littered the ocean floor.

 

“What is that?” Sonic whispered.

 

They moved closer. The beam was vibrating, drilling into the rock. Tails snapped a photo. They drove through the structures. A slanted cave caught Knuckles’ eye, so they decided to investigate. It was pitch black, and seemed to continue for miles in a straight line. Tails turned on the submarine headlights. The cavern was about 30 feet wide and 50 feet tall, and the walls were completely smooth.

 

“This can’t be natural, it’s too perfect,” Tails said. He handed Sonic the camera and clutched the controls. The farther they went the murkier the water became, until the bubble was encased in an alien film. Almost like ink. Unlike the surrounding reef, not so much as a snail clung to the walls. Time came to a halt.

 

“Do you think…”   
  
“This is definitely the work of Eggman,” Sonic said, clutching the camera. The walls had gone from a dark grey to a black similar to what now clung to the bubble. Even the windshield wipers did little to clear their vision.

 

After what felt like days, they bumped into a wall. The cockpit was stifling hot to the point where it was hard to breathe, and they were desperate for air. Tails noticed the bubbles from the propeller floating upwards, and attempted to follow. The cave went straight up at a right angle. The length of the connecting tunnel felt the same as the first, and just as horrendous. The dark water was making Sonic’s skin crawl. They broke the surface into a small stone dome. More machinery lay in dripping heaps around the edge of the pool they floated in. The area was lit by dim lights mounted on tripods. The water was solid black.

 

Tails lowered the bubble, their gasps echoing around them. He scanned the equipment and snapped his fingers.

 

“We should take some of this stuff back to shore, it might tell us more about what’s going on down here.”

 

“Tails how are we gonna get this stuff out?”

 

“Like this!” A long chain shot out of the front of the sub and latched onto a small drill, yanking it back to Tails arms.

 

“I didn’t know you added that! Sonic exclaimed, startled by the sudden movement.

 

Tails blinked. “How was I supposed to show this off..?”

 

He crammed a few scraps into the small compartment space in the back of the sub and put the bubble back. He grappled onto one last larger piece of equipment and kept it hooked to the bottom of the sub, preserving gas by allowing it to weigh them back down the tunnel. Sonic tapped his fingers on the glass.

 

“I hate being in this thing, it’s too cramped. Stuffy, too. I think I’ll stick to land.”

 

Knuckles hadn’t said anything for at least an hour. His head was squished against the bubble and his hat lay flat in his lap. He trembled, restless in his sleep. Sonic hated to admit that was the most peaceful he’d looked all day. With a sigh, he stared out at the abysmal blackness and waited for the tunnel to end.

**Author's Note:**

> This was a dare that took me over a year to finish. I decided to use the countries from Unleashed to give the world a little consistency, and to paint a better visualization of where everything takes place and what it looks like. This is kind of an AU, since Heroes is completely omitted and Shadow remains dead, meaning 06 and Shadow are also off the timeline.


End file.
